<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script type="text/javascript" src="../js/jquery-3.3.1.min.js"></script>
</head>
<style>
    .one{
        width: 300px;
        height: 300px;
        background-color: #ff6700;
    }
</style>
<body>
<input type="button" id="b1" value="添加class">
<input type="button" id="b2" value="移除class">
<input type="button" id="b3" value="切换">

<div>

</div>
</body>
</html>
<script type="text/javascript">
    $("#b1").click(function () {
        $("div").addClass("one");
    })
    $("#b2").click(function () {
        $("div").removeClass("one");
    })
    $("#b3").click(function () {
        $("div").toggleClass("one");
    })
</script>